Monday, March 31, is the last day for open enrollment, when nearly everyone in the U.S. must be signed up for health insurance or risk paying a fee.

That fee won't come to you like a bill in the mail. You'll pay it when you file your taxes next year.

"If you don't meet any of the exemptions, then you will be issued a penalty, which is essentially an extra tax on your return," said Yesenia Barraza, a certified public accountant in Phoenix. "So it might decrease your refund."

It's called the Individual Shared Responsibility Payment. When you file your taxes in 2015, for the 2014 year, you will pay that penalty it in one of two ways, whichever is greater.

The first possibility is a flat fee — $95 per adult and $47.50 per child, up to a $285-per-family maximum.

The second possibility comes from a complicated IRS equation: 1 percent of the total, when you subtract your filing threshold from your income. (Your filing threshold is the dollar amount you must earn to file a return.)

It looks confusing, so the IRS gives an example on its website of a married couple with two kids. Their joint income is $70,000. Subtract their filing threshold of $20,300 and then take 1 percent of the total. You end up with $497.

That total — $497 — is more than the $285 flat fee, so the couple will owe the greater of those two totals: $497. They will pay that fee when they file their taxes in 2015 for 2014.

The Individual Shared Responsibility Payment applies only if you don't have health insurance. So, if you're covered, there's no need to worry. But if you're not covered, you may want to consider logging on to healthcare.gov in these final hours before open enrollment ends for 2014.

The fees will grow each year you're not covered. It's also important to note there will be a cap to these fees, but the IRS has not officially announced what that will be. Some tax groups estimate the cap will be in the thousands, but that remains to be seen.

Problem with a business? Call us. Our trained volunteers take phone calls from 11 a.m. to 1 p.m. Mondays through Fridays at 602-260-1212. Or you can submit your complaint online at call12.azcentral.com.